An undercover London police officer - who tricked women into sexual relations for which Scotland Yard was forced to apologise - spent time in Northern Ireland, environmental campaigners have claimed.

Last month, Scotland Yard issued a public apology as it said five undercover officers abused their police powers to conduct sexual relationships with seven women, one lasting nine years, after they infiltrated protest groups.

The women were compensated for the deception.

The cases came to light following the collapse of a court case against a group of environmental campaigners accused of trying to shut down a coal-fired power station in Nottinghamshire when an undercover officer, Mark Kennedy, offered to give evidence on their behalf.

It emerged that Mr Kennedy, who worked under the cover name of Mark Stone, had relationships with at least three women during a long period infiltrating the environmental movement, according to lawyers.

The BBC is reporting that environmental campaigners are claiming that Mr Kennedy spent time in Northern Ireland and the Republic of Ireland while he was undercover.

They claim that while in Belfast in 2005, Kennedy attended a pub quiz in south Belfast and an anti-globalisation game of bingo in a city centre church.

The PSNI said the unit did not operate in Northern Ireland while the Met would not confirm or deny the claims.

Her Majesty's Inspectorate of Constabularies, which investigated the use of undercover operatives, said Kennedy's unit covered England and Wales and also worked with forces in Scotland and Northern Ireland.